linux-kernel - Re: [PATCH v1] ARM: imx: mach-imx6ul: remove 14x14 EVK specific PHY fixup

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Date:   Thu, 10 Dec 2020 11:15:18 +0100
From:   Sébastien Szymanski 
        <sebastien.szymanski@...adeus.com>
To:     Oleksij Rempel <o.rempel@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>
Cc:     Philippe Schenker <philippe.schenker@...adex.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Russell King <linux@...linux.org.uk>, linux-imx@....com,
        kernel@...gutronix.de, David Jander <david@...tonic.nl>,
        Fabio Estevam <festevam@...il.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v1] ARM: imx: mach-imx6ul: remove 14x14 EVK specific PHY
 fixup

Hi,

On 12/9/20 1:20 PM, Oleksij Rempel wrote:
> Remove board specific PHY fixup introduced by commit:
> 
> | 709bc0657fe6f9f5 ("ARM: imx6ul: add fec MAC refrence clock and phy fixup init")
> 
> This fixup addresses boards with a specific configuration: a KSZ8081RNA
> PHY with attached clock source to XI (Pin 8) of the PHY equal to 50MHz.
> 
> For the KSZ8081RND PHY, the meaning of the reg 0x1F bit 7 is different
> (compared to the KSZ8081RNA). A set bit means:
> 
> - KSZ8081RNA: clock input to XI (Pin 8) is 50MHz for RMII
> - KSZ8081RND: clock input to XI (Pin 8) is 25MHz for RMII

OPOS6UL has a KSZ80801RNB. On this PHY variant, bit 7 of reg 0x1F means:
1: RMII 50MHz clock mode; clock input to XI (Pin 9) is 50MHz
0: RMII 25MHz clock mode; clock input to XI (Pin 9) is 25MHz

> 
> In other configurations, for example a KSZ8081RND PHY or a KSZ8081RNA
> with 25Mhz clock source, the PHY will glitch and stay in not recoverable
> state.
> 
> It is not possible to detect the clock source frequency of the PHY. And
> it is not possible to automatically detect KSZ8081 PHY variant - both
> have same PHY ID. It is not possible to overwrite the fixup
> configuration by providing proper device tree description. The only way
> is to remove this fixup.
> 
> If this patch breaks network functionality on your board, fix it by
> adding PHY node with following properties:
> 
> 	ethernet-phy@x {
> 		...
> 		micrel,led-mode = <1>;
> 		clocks = <&clks IMX6UL_CLK_ENET_REF>;
> 		clock-names = "rmii-ref";
> 		...
> 	};

On OPOS6UL, this fix do fixes network breakage introduced by this patch.
So, for OPOS6UL,

Tested-by: Sébastien Szymanski <sebastien.szymanski@...adeus.com>

> 
> The board which was referred in the initial patch is already fixed.
> See: arch/arm/boot/dts/imx6ul-14x14-evk.dtsi
> 
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
>  arch/arm/mach-imx/mach-imx6ul.c | 21 ---------------------
>  1 file changed, 21 deletions(-)
> 
> diff --git a/arch/arm/mach-imx/mach-imx6ul.c b/arch/arm/mach-imx/mach-imx6ul.c
> index e018e716735f..eabcd35c01a5 100644
> --- a/arch/arm/mach-imx/mach-imx6ul.c
> +++ b/arch/arm/mach-imx/mach-imx6ul.c
> @@ -27,30 +27,9 @@ static void __init imx6ul_enet_clk_init(void)
>  		pr_err("failed to find fsl,imx6ul-iomux-gpr regmap\n");
>  }
>  
> -static int ksz8081_phy_fixup(struct phy_device *dev)
> -{
> -	if (dev && dev->interface == PHY_INTERFACE_MODE_MII) {
> -		phy_write(dev, 0x1f, 0x8110);
> -		phy_write(dev, 0x16, 0x201);
> -	} else if (dev && dev->interface == PHY_INTERFACE_MODE_RMII) {
> -		phy_write(dev, 0x1f, 0x8190);
> -		phy_write(dev, 0x16, 0x202);
> -	}
> -
> -	return 0;
> -}
> -
> -static void __init imx6ul_enet_phy_init(void)
> -{
> -	if (IS_BUILTIN(CONFIG_PHYLIB))
> -		phy_register_fixup_for_uid(PHY_ID_KSZ8081, MICREL_PHY_ID_MASK,
> -					   ksz8081_phy_fixup);
> -}
> -
>  static inline void imx6ul_enet_init(void)
>  {
>  	imx6ul_enet_clk_init();
> -	imx6ul_enet_phy_init();
>  }
>  
>  static void __init imx6ul_init_machine(void)
> 


-- 
Sébastien Szymanski, Armadeus Systems
Software engineer